The present invention relates to amorphous metal alloys. More particularly, it relates to a novel technique for producing a variety of amorphous metal alloys.
Amorphous metal alloys have been studied extensively in the past two decades and have been found to possess a number of superior chemical and physical properties. Among these are excellent corrosion resistance, desirable magnetic properties, and good wear and abrasion resistance.
Heretofore, such alloys have been prepared by several techniques, the most widely used of which being the rapid quenching of the alloy from its melt. While it is possible to produce a variety of different alloys in thin ribbon or wire form in that manner, the technique has inherent limits in the thickness of the stock it can produce and cannot be used to form irregular shapes. Sputtering and plasma deposition have also been used to produce thin foils. As disclosed by A. K. Hayes in U.S. Pat. No. 4,626,448, the latter technique, in particular, has been capable of producing thin adherent coatings of amorphous alloys on relatively large, complex shapes. Both these techniques again are limited in terms of the thickness of deposit that can be formed within a reasonable time without the creation of destructive residual stresses. Electroless nickel plating has also been used to produce a small number of nickel-based amorphous alloys. While the technique has the capability of building thicker deposits, it is rather limited in the variety of alloys that it can produce and does not allow variation of composition and properties during the course of deposition.
An electron beam evaporation process has been disclosed by K. Matsubara in U.S. Pat. No. 3,900,585 for coating a solid metal onto a substrate. However, in that activated evaporation process which utilizes a plasma, the substrate must serve as cathode and, therefore, must be conductive and the resulting coatings are not amorphous. Iron can also be coated onto a substrate by a plasma-enhanced deposition method involving iron pentacarbonyl in a radio-frequency power-induced glow discharge reactor, but again the resulting coating consists of iron crystallites embedded in an iron oxide matrix (D. M. Wroge and D. W. Hess, "Plasma-enhanced Deposition of Iron/Iron Oxide Films" , Report LBL-9879, 1979).
Vapor forming of crystalline nickel is a chemical vapor deposition process that has been employed commercially to form near-net-shape objects such as molds and dies. It deposits nickel metal from nickel carbonyl at a fairly rapid rate (about 200 .mu.m thickness per hour) at moderate temperatures, i.e., about 170.degree. C. It is used to reproduce complex shapes and is virtually unlimited in the thickness of the deposits that it can yield. Deposition of low boron Ni-B alloys, e.g., 0.07 wt% boron (0.38 at.%), has been disclosed by W. C. Jenkin in U.S. Pat. No. 3,355,318. Throughout this application "at.%" stands for "atom%" Skibo and Gruelich also have studied the structure and mechanical properties of chemical vapor deposition (CVD) alloys with boron contents from 0.23 to 1.09 at.% [Thin Solid Films, Vol. 113 (1984) 225]. The chemical vapor deposition process, however, has not been considered suitable so far for the forming of amorphous metal alloys.
In view of the prior art and its limitations, it is an object of this invention to provide a novel technique to produce amorphous metal alloys. Another object is to produce useful stock shapes of amorphous metal alloys such as sheets, tapes, rods, tubing, and the like. A further object is to produce amorphous metal alloys as thick free-standing structures of simple or complex design. A still further object is to provide a technique that can be varied easily and inextensively to produce metal alloys which are layered or which are graded to other compositions that are either amorphous or crystalline. An additional object is to apply thick coatings to other materials, including infiltration of porous materials, such as cloths, felts, or foams.
Additional objects, advantages, and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.